Royal Dutch Shell is set to begin drilling in the Arctic waters off Alaska beginning next month, assuming the Obama Administrations doesn’t hold off on needed permits at the last-minute. (With President Obama fighting for re-election—and fighting the charge that he’s anti-energy—don’t bet on it.) That has environmentalists extremely unhappy. As global warming—ironically—opens up once-iced over parts of the Arctic waters to drilling rigs, greens worry that a spill in the hostile environment of the far North is as inevitable as it would be devastating. Shell and other oil companies interested in the Arctic argue that they’ll be taking extra precautions in the Arctic, and note that they’ll be drilling shallow, low-pressure wells that are less likely to blow out than the deepwater well that caused BP’s 2010 Gulf oil spill.

But a new report by the NGO Clean Air Task Force (CATF) shows that an oil spill isn’t the only risk that Arctic drilling poses to the environment. Methane and black carbon, two potent greenhouses gases, will likely be emitted in significant amounts if drilling in the Arctic proves as lucrative as many oil companies are hoping for. Exactly how much additional greenhouse gas will be released by the production of Arctic oil isn’t clear—and depends on whether drillers and regulators take steps to reduce the warming side effects of drilling. “It’s ironic that climate change has led to the opening of the Arctic for drilling, but we aren’t paying much attention to the climate change that drilling will help cause,” says Jonathan Banks, senior climate policy advisor for CATF and the author of the report.

The main problem isn’t the oil itself—although, of course, if the 90 billion barrels of oil believed to be obtainable in the Arctic are burned in cars or trucks, the carbon released will help undoubtedly help intensify climate change. It’s chiefly the natural gas that will be produced along with that oil. Natural gas is essentially methane—and methane is a powerful, albeit short-lived greenhouse gas, with more than 20 times the warming potential of plain old carbon dioxide. By some estimates, there’s as much as 1.7 trillion cubic ft. of natural gas to be found in the Arctic.

But companies like Shell aren’t braving the elements in the Arctic to bring back natural gas. They’re there for the oil, which is worth far more—and not incidentally, is a lot easier to store and transport than gas. Natural gas either needs a pipeline network that can allow it to be shipped from the well to a consumer, or it needs to be cooled to super-low temperatures, after which it can be shipped on an LNG tanker. (Oil, by contrast, can be loaded without any intermediary steps onto a tanker.) There are neither many pipelines nor many LNG facilities in the far North, which means it’s not easy nor cheap for oil companies to actually do anything with the natural gas they’ll be producing alongside all that lovely oil. “The race in the Arctic is about the oil,” says Banks. “But the gas that goes along with it can be a huge source of carbon.”

Ideally oil companies would capture the natural gas and ship it, either by LNG tanker or pipeline. But that’s not likely given the current energy infrastructure—or lack of it—in the Arctic. Fortunately the gas won’t simply be released into the air—methane is highly combustible, and uncontrollable amounts combustible gas is not something a drilling rig like simply floating around. (See Horizon, Deepwater.) Instead, the next best option is to burn the gas in a controlled process, also known as flaring. Flaring reduces the amount of pure methane reaching the atmosphere, but it can also produce other pollutants—including black carbon, otherwise known as soot.

Black carbon can have a double warming effect. As its name suggests, it warms the atmosphere directly by intensifying the greenhouse effect, just as carbon dioxide does. But as black carbon settles on the snow and ice of the Arctic, it darkens the ground—and that in turn causes the surface to absorb solar energy it would have otherwise reflected back into space. (It’s the albedo effect, which you’ll hopefully remember from 7th grade science class, or at the very least, from the last time you wore a black T-shirt during a hot day.) The albedo of the Arctic is already shifting as sea ice melts, opening up new stretches of dark water to sunlight—the same water in which oil companies will be drilling in the years to come. Black carbon produced by those rigs will only make climate change in the Arctic—where temperatures have increased by 2 to 3 C over the past 50 years—even worse.

So what can be done to make drilling in the Arctic a little more climate-friendly? The CATF report outlines a number of mitigation routes, ranging from vapor recovery units that reduce emissions from vented methane to tighter valves that prevent fugitive emissions to the use of ultra-low sulfur diesel fuel, which cuts black carbon. But mitigation is almost certainly going to require regulation, which will vary in the Arctic. Countries like Norway generally keep a tight hold on their oil industry; countries like Russia, somewhat less so. The U.S. falls in the middle, though it’s notable that regulatory authority is passing from the Environmental Protection Agency to the Department of Interior over time. But regulation is needed. “The potential is here for [production] to be a significant source of greenhouse gases,” says Banks. If oil companies really are going to drill the Arctic, the very least they can do is take every precaution possible, at every stage of the process.